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Fracture mimic example - Growth plates

Lines passing through the acromion and proximal humerus are growth plates - not fractures

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Unfused apophysis

The apophysis of the 5th metatarsal base is often mistaken for a fracture. Here the normal apophysis is orientated nearly longitudinally to the bone. A fracture at this site will typically be perpendicular to the length of the bone shaft.

Another clue is that the bones of an aphophysis will have a rounded and corticated edge. The edge of a fracture will be angulated with no cortication.

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Unfused apophysis example - 5th metatarsal

Note the corticated and rounded edge of the apophysis compared with the sharp and non-corticated edge of the fracture fragment

Accessory ossicles

Accessory ossicles (small bones) are considered normal, but are not present in all individuals. They should not be mistaken for fractures. The best clue is that they have a dense fully corticated edge, whereas the edge of a fracture will not be corticated.

It should be remembered that although usually innocent, accessory ossicles and their surrounding soft tissues can be injured, and become symptomatic.

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Accessory ossicle example - Foot

This patient has an extra bone adjacent to the navicular

This bone is normal - note the corticated edge

Vascular/nutrient lines

Bones are highly vascular structures that are penetrated by nutrient vessels. These appear as low density black lines which often mimic fractures. Characteristically they pass obliquely through the cortex and may have a visible corticated edge. They are not associated with loss of alignment of bone as seen in genuine fractures.

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Vascular lines example - Femur

A well-defined lucent line passes lengthways through the bone

This vascular line passes obliquely through the cortex (lateral image)

A dense (white) corticated edge is a reassuring sign

Harris lines

You may see thin sclerotic lines passing transversely across the shaft of long bones. Although it is important not to overlook a genuine impacted fracture, these commonly seen lines are not pathological, and are considered developmental.